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🎯 核心知识点总结 |
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类别 |
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知识点 |
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接口 |
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接口方法默认是 public abstract,不需要写修饰符 |
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继承 |
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extends 后直接跟类名,不加括号 |
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构造函数 |
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子类必须调用父类存在的构造函数 |
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抽象方法 |
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普通子类必须实现所有抽象方法 |
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创建对象 |
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格式:类名 变量名 = new 类名(参数); |
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类体结构 |
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执行语句必须在方法中,不能直接在类体中 |
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方法调用 |
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println() 只能用 + 连接字符串,不能用逗号 |
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标点符号 |
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Java 代码必须使用英文标点 |
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语句结束 |
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每条语句必须以分号 ; 结尾 |
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package W6; |
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public abstract class Animal { |
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private String name; |
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private int age; |
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public Animal(String name, int age) { |
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this.name = name; |
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this.age = age; |
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} |
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public int getAge() { |
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return age; |
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} |
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public String getName() { |
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return name; |
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} |
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public void setName(String name){ |
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this.name=name; |
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} |
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public void setAge(int age){ |
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this.age=age; |
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} |
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public abstract void makeSound(); |
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} |
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interface Swimmable{ |
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public void swim(); |
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} |
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class Dog extends Animal implements Swimmable{ |
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public Dog(String name,int age){ |
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super(name,age); |
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} |
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@Override |
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public void makeSound(){ |
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System.out .println("发出叫声:汪汪汪!!"); |
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} |
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@Override |
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public void swim() { |
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System.out.println(getName()+"正在游泳"); |
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} |
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} |
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class Cat extends Animal{ |
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public Cat(String name,int age){ |
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super(name,age); |
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} |
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public void makeSound(){ |
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System.out.println("发出叫声:喵喵喵!!"); |
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} |
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} |
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class Main{ |
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static void main(String[] args) { |
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Dog dog = new Dog("耶耶", 5); |
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System.out.println(dog.getName()+dog.getAge()+"岁了"); |
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dog.swim(); |
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dog.makeSound(); |
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Cat cat = new Cat("小咪",3); |
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System.out.println(cat.getName()+cat.getAge()+"岁了"); |
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cat.makeSound(); |
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} |
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} |
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